1. Field of the Invention
The present invention relates to a wireless transmission system, a wireless communication device, and a wireless communication method.
2. Description of the Related Art
For example, low voltage differential signaling (LVDS) is known as a technique for realizing high-speed signal transmission between pieces of electronic apparatus disposed at a comparatively-short distance (e.g. within several centimeters to ten and several centimeters) and high-speed signal transmission in electronic apparatus. However, along with recent further increases in the size and transmission speed of transmission data, increase in the power consumption, increase in the influence of signal distortion due to reflection and so forth, increase in unnecessary radiation, etc. become problems. For example, the performance of the LVDS is reaching the limit in the case of high-speed (real-time) transmission of e.g. video signals (including imaging signals) and computer image signals in apparatus.
It would be possible to increase the number of lines and parallelize the signal transmission to thereby decrease the transmission speed per one signal line in order to address the problems in increasing the transmission speed of transmission data. However, this countermeasure leads to increase in the number of input/output terminals. As a result, increase in the complexity of the printed board and cable lines, increase in the semiconductor chip size, and so forth are required. Furthermore, because high-speed, large-size data are routed by the lines, so-called electromagnetic interference becomes a problem.
Both of the problems in the LVDS and the technique of increasing the number of lines are attributed to the signal transmission by the electrical lines. Thus, as a technique for solving the problems attributed to the signal transmission by the electrical lines, techniques of transmitting signals with replacement of the electrical lines by wireless transmission have been proposed (refer to e.g. Japanese Patent Laid-open No. 2005-204221 (hereinafter, patent document 1), Japanese Patent Laid-open No. 2005-223411 (hereinafter, patent document 2), Japanese Patent Laid-open No. Hei 10-256478 (hereinafter, patent document 3), and U.S. Pat. No. 5,754,948 (hereinafter, patent document 4)).
Patent documents 1 and 2 propose that signal transmission in a housing is performed by wireless transmission and the ultra wide band (UWB) communication system is employed. Patent documents 3 and 4 show that a carrier frequency in the millimeter wave band is used.